Tag Archives: Convex polytopes

Karim Adiprasito: Flag simplicial complexes and the non-revisiting path conjecture (A combinatorial proof of the Adiprasito-Benedetti theorem.)

Posted on November 12, 2012 by Gil Kalai

This post is authored by Karim Adiprasito The past months have seen some exciting progress on diameter bounds for polytopes and polytopal complexes, both in the negative and in the positive direction.  Jesus de Loera and Steve Klee described simplicial polytopes which are not  … Continue reading →

Posted in Convex polytopes, Guest blogger | Tagged , , , | Leave a comment

Tokyo, Kyoto, and Nagoya

Posted on August 20, 2012 by Gil Kalai

Near Nagoya: Firework festival; Kyoto: with Gunter Ziegler; with Takayuki Hibi, Hibi, Marge Bayer, Curtis Green and Richard Stanly; Tokyo: Peter Frankl; crowded crossing. Added later: Mazi and I at the same restaurant taken by Stanley. I just returned from … Continue reading →

Posted in Combinatorics, Conferences, Convex polytopes | Tagged , , , | 2 Comments

Projections to the TSP Polytope

Posted on December 7, 2011 by Gil Kalai

Michael Ben Or told me about the following great paper Linear vs. Semidefinite Extended Formulations: Exponential Separation and Strong Lower Bounds by Samuel Fiorini, Serge Massar, Sebastian Pokutta, Hans Raj Tiwary and Ronald de Wolf. The paper solves an old conjecture … Continue reading →

Posted in Computer Science and Optimization, Convex polytopes | Tagged , , , | 1 Comment

Test Your Intuition (12): Perturbing a Polytope

Posted on May 12, 2010 by Gil Kalai

Let P be a d-dimensional convex polytope. Can we always perturb the vertices of P moving them to points with rational coordinates without changing the combinatorial structure of P? In order words, you require that a set of vertices whose … Continue reading →

Posted in Convex polytopes, Test your intuition | Tagged , | 4 Comments

The Polynomial Hirsch Conjecture: Discussion Thread, Continued

Posted on October 6, 2009 by Gil Kalai

Here is a  link for the just-posted paper Diameter of Polyhedra: The Limits of Abstraction by Freidrich Eisenbrand, Nicolai Hahnle,  Sasha Razborov, and Thomas Rothvoss. And here is a link to the paper  by Sandeep Koranne and Anand Kulkarni “The d-step Conjecture is Almost true”  – … Continue reading →

Posted in Convex polytopes, Open discussion, Open problems | Tagged , | 16 Comments

Igor Pak’s “Lectures on Discrete and Polyhedral Geometry”

Posted on August 27, 2009 by Gil Kalai

Here is a link to Igor Pak’s  book on Discrete and Polyhedral Geometry  (free download) . And here is just the table of contents. It is a wonderful book, full of gems, contains original look on many important directions, things that … Continue reading →

Posted in Book review, Convex polytopes, Convexity | Tagged , , , | 4 Comments

Five Open Problems Regarding Convex Polytopes

Posted on May 7, 2008 by Gil Kalai

   The problems  1. The conjecture A centrally symmetric d-polytope has at least non empty faces. 2. The cube-simplex conjecture For every k there is f(k) so that every d-polytope with has a k-dimensional face which is either a simplex … Continue reading →

Posted in Combinatorics, Convex polytopes, Convexity, Open problems | Tagged , , , | 20 Comments